1. Field of the Invention
The present invention relates to a floating image display device for displaying a floating image in the air where there are no display elements.
2. Description of the Related Art
Devices employing floating image display technology, for displaying a floating image in the air where there are no display elements, have been devised. For example, International Publication WO2014/041977 (Patent Document 1) discloses a device that generates a floating image by use of a plasma emission phenomenon of laser plasma and a device that uses a floating image, displayed by projecting multiple laser beams to make the beams intersect in the air, as an alternative to a wall, a partition, an entrance/crossing gate at a railway crossing or a station's ticket barrier. However, it is undesirable to place a floating image generated by use of the plasma emission phenomenon in the vicinity of a human body. Further, the method of displaying a floating image by projecting multiple laser beams needs a countermeasure for preventing the laser beams from directly entering a human eye.
In such a circumstance, there has been devised a technology for projecting a display image displayed on a flat panel display or the like onto a space in the air where there are no display elements. For example, Japanese Patent Application Publication No. 2009-276698 (Patent Document 2) discloses a technology that employs a dihedral corner reflector array formed by arranging a great number of dihedral corner reflectors on a plane, and thereby forms a floating image from the display image in a space at a position plane-symmetrical with respect to the dihedral corner reflector array to display the floating image as a real image in the air.
Further, Japanese Patent Application Publication No. 2009-25776 (Patent Document 3) discloses a technology that employs a half mirror and a retroreflective sheet, and thereby forms a floating image from the display image in a space at a position plane-symmetrical with respect to the half mirror to display the floating image as a real image in the air.
In the floating image displayed in the air by using the technology described in Patent Document 2 or Patent Document 3, part of optical paths for forming the floating image are interrupted by a hand or body of a person moving through the floating image, and thus part of the floating image is not formed and there are cases where a person viewing the floating image (viewer or waiting person) has a feeling of strangeness or physiological discomfort.